Apparatus of this kind are known in general and are called liquid or water dams or weirs. The partition or dam wall is raised and lowered in response to a water level gauge, such as a pressure gauge. The gauge controls a drive means which is operatively connected to the partition or dam wall so as to raise or lower the same accordingly thus permitting excess water to flow off over the upper edge of the partition or dam wall.
This type of control of the water level is rather expensive both in structure and control and thus susceptible of trouble.